Universe Faces Big Crunch in 33 Billion Years, Data Shows

Physicists at Cornell University have analyzed recent data from two large dark energy projects and found signs that the universe will not keep expanding forever. Instead, it may hit a peak size in roughly 11 billion years and then shrink back to a single point in a big crunch about 20 billion years later, making the total life of the cosmos around 33 billion years.

Background

The universe started with the big bang 13.8 billion years ago. Since then, it has grown larger, pulled by a force called dark energy that makes up most of what exists. For years, scientists thought this dark energy would make the universe expand faster and faster without stop. That idea came from a number called the cosmological constant, which Albert Einstein added to his equations over 100 years ago to keep the universe steady. Later, after Edwin Hubble showed the universe is growing, researchers brought back the constant but saw it as positive, speeding up expansion.

Two big projects changed the picture this year. The Dark Energy Survey in Chile and the Dark Energy Spectroscopic Instrument in Arizona measured how galaxies move and cluster. These efforts aimed to check if dark energy is just a steady constant. The results did not match that simple view. Instead, they hint at something more complex, where dark energy might act like a negative constant now.

A negative constant would slow down growth over time. Gravity would win out, pulling everything back together. This matches old ideas from the 1920s by Alexander Friedmann, but new data gives a timeline.

Key Details

Cornell physicist Henry Tye and his team added the fresh data to a model with the cosmological constant. Their work came out in the Journal of Cosmology and Astroparticle Physics. The model shows the universe is about halfway through its life. It will grow to its biggest in 11 billion years. Then, expansion stops. Contraction starts, leading to a big crunch in another eight to 20 billion years.

“The new data seem to indicate that the cosmological constant is negative, and that the universe will end in a big crunch.” – Henry Tye, Cornell University physicist

Tye points out that a negative constant is not a new thought. What stands out is the timing and path of the collapse. The model fits data from both observatories, which agree despite being in different parts of the world.

The Role of Dark Energy

Dark energy makes up 68 percent of the universe's mass and energy. Past views treated it as fixed. Now, Tye's group suggests a light particle that acted like a constant early on but changed. This shift makes the effective constant negative, tipping the balance toward crunch.

Other studies back this up. Data from supernovae, when fixed for age errors, show expansion already slowing today. Baryon acoustic oscillations and cosmic microwave background measures also point to deceleration, not speedup.

What This Means

If the data holds, the universe enters a crunch phase far sooner than many expected. No more endless expansion or big freeze, where everything spreads thin and cold. No big rip tearing atoms apart. Just a return to one point.

Some researchers talk of a big bounce after crunch, where collapse sparks a new big bang in a cycle. But Tye's model ends at the crunch. Confirmation needs more data. Upcoming telescopes like the Vera C. Rubin Observatory will spot thousands of supernovae to test these ideas.

For now, expansion keeps going, even speeding up a bit in spots. But the peak looms in 11 billion years. Earth and stars will change long before then, with our sun dying in five billion years. Humanity, if it lasts, faces vast time scales.

Tye notes the model gives clear steps: peak size, then steady shrink under gravity boosted by negative dark energy. Other teams see evolving dark energy weakening fast, matching the slowdown.

Researchers in South Korea, led by Young-Wook Lee at Yonsei University, used cleaned supernova data with other measures. They ruled out the standard model and said expansion decelerates now. This lines up with Tye's timeline.

“People have said before that if the cosmological constant is negative, then the universe will collapse eventually. That’s not new. However, here the model tells you when the universe collapses and how it collapses.” – Henry Tye

Ongoing work tests these findings without relying on supernova ages alone. In five years, better maps of galaxies could settle if dark energy evolves and drives a crunch. Until then, the universe grows, but its end draws a defined line.